1. Field of the Invention
The present invention relates to a pipeline diagnostic system and method, and more particularly, to a vibratory pipeline diagnostic system and method.
2. Statement of the Problem
Pipelines are used for transporting many types of gases and fluids. A pipeline, whether buried or above ground, can transport such materials for hundreds or even thousands of miles. Oil and natural gas pipelines are just two examples of materials that are transported via extensive networks of pipelines.
Pipelines are designed to be used for many years. However, they cannot last forever. If the material being transported is at least partially corrosive, then the wall of the pipeline can be gradually corroded away over time. This can lead to a weakening and ultimately to a rupture of the pipeline. In addition, if the material being transported includes solid particles, such as sand or other geological particles, the flowing material can erode the pipeline wall. This erosion process can also thin and weaken the pipeline wall.
Other damage to a pipeline is also possible. For example, machinery operating in the vicinity can impact and damage the pipeline. If a wall portion of the pipeline is deformed by an impact, the structural integrity of the pipeline will be affected. In addition, there is the possibility that inherent flaws in the pipeline wall can eventually manifest due to use of the pipeline, such as if the pipeline is pressurized to an appreciable pressure level.
There are many prior art diagnostic devices and methods that are available for checking on the condition of a pipeline. A pipeline can be visually inspected from the outside. However, this prior art method is very time-consuming, tedious, and expensive. In addition, such inspection may not be able to find flaws internal to the pipeline, such as corrosion and erosion, or at least until the problems become severe enough to cause a leak.
One prior art inspection device is referred to as a pig. A pig is an electronic inspection device that is passed through a section of pipeline. The pig can perform electronic scanning of the interior of the pipeline and can relay signals or data to an external station by wires or radio signals. However, a prior art pig has drawbacks, too. The prior art pig in some cases requires the material flow to be shut down and the pig transits the empty pipeline. Alternatively, the pig can be employed with the pipeline having material flow, wherein the pig is carried through the pipeline by the material flow. Some flow cessation may be required for the insertion and removal processes, however. As a consequence, the prior art pig requires cumbersome and time-consuming insertion and removal procedures.
Another prior art diagnostic device is shown in U.S. Patent Publ. 2005/0279169 to Lander. Lander includes an array of vibration sensors that are attached to the pipeline at intervals and discloses that a leak in a pipeline will cause a characteristic vibration to be produced. Lander discloses that the leak can be detected by detecting these characteristic vibrations. The drawback to this prior art approach is that the system is completely passive and cannot generate vibrations. In addition, the system of Lander cannot detect developing weaknesses in the pipeline, and cannot detect future flaws or problems in the pipeline. The system of Lander cannot detect or determine a problem until a leak develops. The system of Lander does not enable a pipeline to be maintained in order to prevent flaws or thinning in the pipeline from developing into serious leaks.
There remains a need for a diagnostic system and method for detecting structural degradation caused by corrosion, erosion, and other physical impacts in order to prevent leakage, avoid environmental impacts and impact costs, and minimize maintenance costs and downtime.